The developing fetus normally receives the majority of its nutrients across the placental circulation. Since the fetus also swallows up to 500 ml of amniotic fluid each day, it has been suggested that absorption of nutrients from swallowed amniotic fluid might play a role in normal fetal nutrition. Provision of supplemental nutrients to the fetus via the intestinal tract may also be possible when placental transfer of nutrients is inadequate for normal growth. Using a chronic sheep preparation, with indwelling fetal and maternal catheters, we have been evaluating the contribution of gastrointestinal absorption to fetal nutrition and whether nutrients can be safely provided through the intestine in the normal and compromised fetus. Gastrointestinal uptake of glucose, fructose, amino acids, lactate and oxygen have been determined from measurements of the concentration of these substances in fetal blood entering and leaving the intestinal tract and from measurements of blood flow to the intestine. We have found that under normal conditions these nutrients are not gained across the fetal intestine but they are rapidly taken up when they are instilled into the gastrointestinal tract. We are now evaluating the effect of enteral provision of substrates on fetal umbilical uptake of nutrients, oxygen consumption, acid-base balance, blood urea nitrogen and ammonia concentrations. The response of normal, hypoxemic and experimentally growth retarded fetuses will be compared.